Apparatus and method for calibration of transmitter in communication device

Abstract

A method and an apparatus for calibration of a transmitter not having a Surface Acoustic Wave (SAW) filter are provided. The apparatus includes a calibration unit for outputting a detuning signal by which a resonance frequency of a Radio Frequency (RF) circuit is detuned with respect to a transmit operating frequency, and an RF unit for changing the resonance frequency according to the detuning signal and for outputting an out-of-band noise and a transmit signal having a relatively lower power than that of a case where the resonance frequency and the transmit operating frequency are tuned to each other.

What is claimed is: 
     
       1. A communication apparatus, the apparatus comprising:
 a calibration unit configured to output a detuning signal by which a resonance frequency of a Radio Frequency (RF) circuit is detuned with respect to a transmit operating frequency; and 
 an RF unit configured to change the resonance frequency based on the detuning signal and configured to output an out-of-band noise and a transmit signal having a relatively lower power than that of a case where the resonance frequency and the transmit operating frequency are tuned to each other. 
 
     
     
       2. The apparatus of  claim 1 , wherein the detuning signal comprises a signal for controlling a reactance value of a variable reactance element included in the RF circuit. 
     
     
       3. The apparatus of  claim 1 , wherein the RF circuit is further configured to change a resonance frequency of BALance-UNbalance (BALUN) included in the RF circuit according to the detuning signal. 
     
     
       4. The apparatus of  claim 1 , wherein the calibration unit is further configured to output the detuning signal which changes the resonance frequency to a lower frequency when the receive frequency band is higher than the transmit frequency band, and to output the detuning signal which changes the resonance frequency to a higher frequency when the receive frequency band is lower than the transmit frequency band. 
     
     
       5. The apparatus of  claim 1 , wherein, before changing the detuning signal, the calibration unit is further configured to control the RF circuit such that an output power of the RF circuit is maximized. 
     
     
       6. The apparatus of  claim 1 , wherein, before changing the detuning signal, the calibration unit is further configured to control the RF circuit such that a maximum output power at the transmit operating frequency is greater than a target value. 
     
     
       7. The apparatus of  claim 6 , wherein the calibration unit is further configured to provide an input code for maximizing output swing to a Digital-to-Analog Converter (DAC) in the RF circuit, to control a gain to maximize voltage swing of a BaseBand Amplifier (BBA) in the RF circuit, and to provide a bias for maximizing a linearity condition to a mixer and a Pre-Power Amplifier (PPA) in the RF circuit. 
     
     
       8. The apparatus of  claim 1 , wherein after the completion of power control using the detuning signal, the calibration unit is further configured to perform additional power control by changing at least one control value among values of elements in the RF circuit. 
     
     
       9. The apparatus of  claim 8 , wherein, after the completion of the additional power control, the calibration unit is further configured to determine an offset for each gain step and store the calibration result. 
     
     
       10. The apparatus of  claim 9 , wherein the calibration result includes at least one of the resonance frequency value, a reactance value corresponding to the resonance frequency, a setup value of elements in the RF circuit, and the step-wise offset values. 
     
     
       11. The apparatus of  claim 1 , further comprising:
 a power amplifier configured to amplify a signal which is output to the RF circuit not subjected to band filtering. 
 
     
     
       12. A method for calibration of a communication device, the method comprising:
 outputting a detuning signal by which a resonance frequency of a Radio Frequency (RF) circuit is detuned with respect to a transmit operating frequency; 
 changing the resonance frequency according to the detuning signal; and 
 outputting an out-of-band noise and a transmit signal having a relatively lower power than that of a case where the resonance frequency and the transmit operating frequency are tuned to each other. 
 
     
     
       13. The method of  claim 12 , wherein the detuning signal includes a signal for controlling a reactance value of a variable reactance element included in the RF circuit. 
     
     
       14. The method of  claim 12 , wherein the changing of the resonance frequency comprises changing a resonance frequency of BALance-UNbalance (BALUN) included in the RF circuit according to the detuning signal. 
     
     
       15. The method of  claim 12 , wherein the outputting of the detuning signal comprises:
 outputting the detuning signal which changes the resonance frequency to a lower frequency when the receive frequency band is higher than the transmit frequency band; and 
 outputting the detuning signal which changes the resonance frequency to a higher frequency when the receive frequency band is lower than the transmit frequency band. 
 
     
     
       16. The method of  claim 12 , further comprising, before changing the detuning signal, controlling the RF circuit such that an output power of the RF circuit is maximized. 
     
     
       17. The method of  claim 12 , further comprising, before changing the detuning signal, controlling the RF circuit such that a maximum output power at the transmit operating frequency is greater than a target value. 
     
     
       18. The method of  claim 17 , wherein the controlling of the RF circuit such that a maximum output power at the transmit operating frequency is greater than a target value comprises:
 providing an input code for maximizing output swing to a Digital-to-Analog Converter (DAC) in the RF circuit; 
 controlling a gain to maximize voltage swing of a BaseBand Amplifier (BBA) in the RF circuit; and 
 providing a bias for maximizing a linearity condition to a mixer and a Pre-Power Amplifier (PPA) in the RF circuit. 
 
     
     
       19. The method of  claim 12 , further comprising, after the completion of power control using the detuning signal, performing additional power control by changing at least one control value among values of elements in the RF circuit. 
     
     
       20. The method of  claim 19 , further comprising:
 after the completion of the additional power control, determining an offset for each gain step; and 
 storing the calibration result. 
 
     
     
       21. The method of  claim 20 , wherein the calibration result includes at least one of the resonance frequency value, a reactance value corresponding to the resonance frequency, a setup value of elements in the RF circuit, and the step-wise offset values. 
     
     
       22. The method of  claim 12 , further comprising amplifying a signal which is output to the RF circuit not subjected to band filtering.